Zero: Black Blood(2014)

Zero: Black Blood is an anime series following Rei Suzumura, the Silver Fanged Knight, as he uncovers a dark secret in a seemingly peaceful commune. The white Horror Ring has established a settlement where humans and supernatural creatures coexist—but only through a sinister monthly sacrifice. One human must be devoured to maintain the fragile peace. Tasked with dismantling this arrangement, Rei teams up with Makai Priest Cain and trainee knight Yuna, who is connected to the operation through her mother, Priestess Iyu. The Makai Senate demands they liberate the trapped humans and eliminate Ring. As Rei investigates, he discovers the true nature of the Horror Ring's control and the moral complexity of the commune's existence. The series blends supernatural action with darker themes of sacrifice and manipulation.